Fig. 1. (  A ) Pain behavior scores in rats that received intraperitoneal saline or Sazetidine-A (mean ± SEM). Scores after administration of the lowest doses of Sazetidine-A (0.125–0.25 mg/kg) were similar to those observed after saline. Pain scores after administration of the highest doses of Sazetidine-A (0.5–1–2 mg/kg) were significantly lower than after saline or the 0.125- to 0.25-mg/kg doses in phases 1 and 2 of the formalin pain test (*  P < 0.0001). (  B ) Pain behavior scores in rats that received intraperitoneal saline or Sazetidine-A (mean ± SEM). Pain scores after epibatidine (2.5–5 μg/kg) were significantly lower than those after saline (*  P < 0.001) and significantly higher than those after Sazetidine-A (0.5–2 mg/kg) (*  P < 0.01) in phases 1 and 2 of the formalin pain test.